how to add the dropdownlist value without using database

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C#5.0

In run mode as follows

Factuly Name Textbox1
Faculty Department Dropdownlist1
(Accounts Department)
(Admin Department)
(Sales Department)
(HR Department)


In the above Dropdownlist1 4 Department is there.suppose i want to add one more department means how can i add with out adding manuallly to database.

And also idont want to add in aspxpage manually like this as follows

Dropdownlist1.items.add("Purchase Department)

how to add value to dropdownlist in run mode.

i want to typethe value in dropdownlist1.

for that how can i asp.net usingc#.